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Re: Reviving HTTP Header Linking: Some code and use-cases

From: Julian Reschke <julian.reschke@gmx.de>
Date: Sat, 15 Mar 2008 10:10:49 +0100
Message-ID: <47DB9299.5070301@gmx.de>
To: Mark Nottingham <mnot@mnot.net>
CC: Harry Halpin <hhalpin@ibiblio.org>, ietf-http-wg@w3.org

Mark Nottingham wrote:
>>   Relationship values are URIs that identify the type of link.  If the
>>   relationship is a relative URI, its base URI MUST be considered to be
>>   "http://www.iana.org/assignments/link-relations.html#", and the value
>>   MUST be present in the link relation registry.
>>
>> JRE: why a new base URI? What's wrong with 
>> "http://www.iana.org/assignments/relation/" 
>> (<http://greenbytes.de/tech/webdav/rfc4287.html#rfc.section.4.2.7.2>)?
> 
> Hmm. That's the actual URI of the registry; we should ping IANA on this, 
> but yes.

Atom specifies <http://www.iana.org/assignments/relation/>.

The page at <http://www.iana.org/assignments/link-relations.html> does 
not provide anchors, so appending a fragment identifier currently has no 
effect.

I was going to claim:

"However, appending the relation name to 
<http://www.iana.org/assignments/relation/> indeed gets you to the 
registration, such as with <http://www.iana.org/assignments/relation/edit>."

...but that is unfortunately not true, because IANA uses 
<http://www.iana.org/assignments/link-relations/> as a base URI, which 
of course is *totally* confusing.

This mismatch should be resolved in some way, be it by fixing the IANA 
web site, or by changing the base URI in the specification (which of 
course will result in Brian complaining even more :-).

>>   to map the profiled link relations to URIs.  For example, in HTML:
>>
>>   <html>
>>     <head profile="http://example.com/profile1/">
>>       <link rel="foo" href="/foo">
>>     </head>
>>     [...]
>>
>>
>>   could be represented as a header like this;
>>
>>   Link: </foo>; rel="http://example.com/profile1/foo"
>>
>> JRE: do we need to talk about profile URIs where concatenation does 
>> not work well, such as "http://www.w3.org/2003/g/data-view"?
> 
> I'm not sure; I thought about it, but would like to see a use case where 
> it's important. Not that there isn't one, but my limited imagination 
> couldn't come up with one at 10pm last night.

I'm also not sure whether it's our problem, but it is a question a 
reader of the spec may ask.

For instance, with the profile URI for GRDDL being 
<http://www.w3.org/2003/g/data-view>, would the absolute URI in the link 
header be

   <http://www.w3.org/2003/g/data-viewtransform>

or

   http://www.w3.org/2003/g/data-view/transform>

or something else?

We may not need to specify that, but if we don't, it may be good to 
state that the party defining the link relation should also specify the 
absolute URI.

 > ...

BR, Julian
Received on Saturday, 15 March 2008 09:11:39 GMT

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